CN101650170B - Detection method of wafer surface roughness - Google Patents

Abstract

The invention provides a detection method of wafer surface roughness, comprising the following steps: selecting at least three wafers with different roughness to serve as samples from the same batch of wafers; detecting each sample by a roughness tester to obtain respective roughness; detecting each sample by an optical tester to obtain respective reflection degree; building a comparison expression between the roughness and the reflection degree; respectively detecting the same batch of wafers one by one by the optical tester to obtain the reflection degree of each wafer; according to the comparison expression, obtaining the roughness of each wafer. The invention can detect the roughness of the wafer surface in real time, which is favourable for improving the quality of the wafer.

Description

Detection method of wafer surface roughness

Technical field

The present invention relates to a kind of semiconductor technology, and relate in particular to a kind of detection method of wafer surface roughness.

Background technology

For the detection of surfaceness, people are with master body or appearance piece the earliest, touch through visual inspection or with hand, and surfaceness is made Comprehensive Assessment qualitatively.Nineteen twenty-nine, the Shi Maerci (g.schmalz) of Germany at first carried out quantitative measurment to the degree of depth of surperficial nao-and micro relief.The Ai Bute of the U.S. in 1936 (e.j.abbott) succeeds in developing the contourgraph of the measure surface roughness of using between first chassis.Britain taylor-hobson company succeeded in developing surfagauge " Tai Lvsaifu (talysurf) " in 1940.After, various countries develop the instrument of multiple measure surface roughness again in succession.At present, measure surface roughness method commonly used has: relative method, light cross-section method, interferometric method, pin are retouched method and impression method etc., and measurement is convenient rapidly, the measured value precision is higher, application is exactly to adopt pin to retouch the surfagauge of method principle the most widely.Pin is retouched method and is claimed tracer method again.When contact pilotage directly streaks on the workpiece measured surface gently; Because measured surface profile peak valley rises and falls; Contact pilotage will produce on perpendicular to tested profile surface direction and move up and down; Cross electronic installation to this Mobile Communication and amplify signal, through nulling table or other output unit that the data or the figure output of relevant roughness is next then.

Roughness tester is used for measuring room and high-precision measurement is carried out to the working surface roughness in the production scene, and roughness tester adopts the contact mode, can measure surface roughness value rapidly accurately and visually; Instrument adopts the inductance type probe, and measuring error is little, good reproducibility; The diamond contact pilotage is durable in use, disposes 16 chip microprocessors, and intelligent degree is high; It is convenient especially to use, and can read required parameter rapidly, and can print whole test datas and contour pattern as required; LCD can show the stylus position in the measuring process, and avoiding the people is the error that causes.

Roughness is the deviation of real surface with the fractional value scope on regulation plane, and is for example shown in Figure 1, and Fig. 1 is the amplification situation synoptic diagram of surfaceness, and it has the Feng Hegu of many little close, and it is the sign of crystal column surface texture.The surface micro roughness concentration height difference of crystal column surface highs and lows, its unit is nanometer or dust.The standard of roughness representes with root mean square, it be the regulation plane all measure numerical value square the square root of mean value.This is a common statistical method that is used for confirming most probable measurement data.

To chip manufacturing; The roughness of crystal column surface is considerable to back metal thin film deposition adhesiveness, and therefore, the roughness of crystal column surface needs real-time monitoring; To guarantee to produce high-quality wafer; And existing roughness method of testing be with wafer one by one be put into the roughness tester test of going down, the time that is spent is longer, can't accomplish real-time monitoring at all.

Summary of the invention

The problem that the present invention solves is that wafer surface roughness can't be realized the problem of detection in real time in the prior art.

The invention provides a kind of detection method of wafer surface roughness, the wafer that comprises the steps: from same batch wafer, to pick out at least three different roughness is as sample; Each said sample is put under the roughness tester detects, draw roughness separately; Each said sample is put under the optical detector detects, draw reflectance separately; Set up the relational expression between said roughness and the said reflectance; Same batch wafer is detected through optical detector one by one, draw the reflectance of each said wafer,, draw the roughness of each said wafer according to said relational expression.

Optional, said sample is the wafer of six different roughness.

Optional, said relational expression is a linear relation.

Optional, with least square method the value of said roughness and said reflectance is carried out match, set up said relational expression.

Owing to adopted technique scheme; Compared with prior art, the present invention has the following advantages: the present invention has replaced roughness tester with optical detector, because the direct detection of optical detector is reflectance; Therefore can realize real-time detection; Set up the relational expression between roughness and the reflectance in addition in advance, just can obtain the roughness of wafer in real time, thereby guaranteed that the wafer of producing is high-quality wafer by real-time detected reflectance.

Description of drawings

Fig. 1 is the amplification situation synoptic diagram of surfaceness;

Fig. 2 is the process flow diagram of detection method of wafer surface roughness of the present invention;

Fig. 3 is the synoptic diagram that concerns of the roughness of detection method of wafer surface roughness one embodiment of the present invention and reflectance.

Embodiment

Do detailed explanation below in conjunction with the accompanying drawing specific embodiments of the invention.

At first, please refer to Fig. 2, Fig. 2 is the process flow diagram of detection method of wafer surface roughness of the present invention, and as can be seen from Figure 2, the present invention includes following steps: step 11: the wafer of from same batch wafer, picking out at least three different roughness is as sample; Step 12: each said sample is put under the roughness tester detects, draw roughness separately; Step 13: each said sample is put under the optical detector detects, draw reflectance separately; Step 14: set up the relational expression between said roughness and the said reflectance, the universal relation formula is a linear relation; Step 15: same batch wafer is detected through optical detector one by one, draw the reflectance of each said wafer,, obtain the roughness of each said wafer according to said relational expression.

Below, please see an embodiment.

At first, the wafer of from same batch wafer, picking out six different roughness is as sample, and sample size generally is not lower than three; Because if sample size very little, can have influence on the degree of accuracy of the unknown number that relates in the relational expression in the future, if simple from the degree of accuracy angle; The quantity of sample is The more the better, still, also will consider the efficient of practical operation; Therefore, present embodiment is chosen as six with the quantity of sample.

Then, six samples are put under the roughness tester one by one detect, be numbered 1-6 respectively for six samples, suppose that y is the roughness of sample; Obtain testing result y1=1980 dust, y2=1760 dust, y3=1620 dust; The y4=1100 dust, y5=1000 dust, y6=650 dust.Then six samples are put under the optical detector one by one and detect, suppose that x is the reflectance of sample, obtain testing result x1=0.08 dust, x2=0.144 dust, x3=0.203 dust, x4=0.386 dust, x5=0.496 dust, x6=0.75 dust.

Below, set up the relational expression between said roughness and the said reflectance.At first roughness and the reflectance with each sample combines; An x-y rectangular coordinate system the inside; Each sample is expressed as a point, and the longitudinal axis is represented roughness, and transverse axis is represented reflectance; Promptly as shown in Figure 3, Fig. 3 is the synoptic diagram that concerns of the roughness of detection method of wafer surface roughness one embodiment of the present invention and reflectance.

Then, use the value of least square fitting roughness and reflectance, draw relational expression each other, computation process is following:

When the data with roughness and reflectance are depicted in the x-y rectangular coordinate system, find that these six points near straight line, therefore, make this straight-line equation following:

Y＝a ₀+a ₁X (1-1)

Wherein Y representes roughness arbitrarily, and X representes reflectance arbitrarily, a ₀And a ₁Be any real number.Then, order

Wherein yi promptly representes y1 to y6 when i=1 to 6.

Equality (1-1) substitution equality (1-2) is obtained:

Follow function

To a ₀And a ₁Ask partial derivative respectively, and make partial derivative equal zero, just can only be contained unknown number a ₀And a ₁A system of equations:

$\left\{\begin{array}{c}6*a_0+\left(\underset{i=1}{\overset{6}{\mathrm{\Σ}}}\mathrm{xi}\right)*a_1=\underset{i=1}{\overset{6}{\mathrm{\Σ}}}\mathrm{yi}\\ \left(\underset{i=1}{\overset{6}{\mathrm{\Σ}}}\mathrm{xi}\right)*a_0+\left(\underset{i=1}{\overset{6}{\mathrm{\Σ}}}{\mathrm{xi}}^2\right)*a_1=\underset{i=1}{\overset{6}{\mathrm{\Σ}}}\mathrm{xi}\end{array}\right.---(1-4)$

With the value of x1 to x6 and the value substitution system of equations (1-4) of y1 to y6, calculate a ₀=-2358, a ₁=2114, the relational expression that draws thus between roughness and the reflectance is:

Y＝-2358+2114*X (1-5)

In order to judge the good and bad of least square fitting situation, generally pass through perhaps " R of related coefficient " R " ²" weigh, as perhaps " R of related coefficient " R " ²" more near 1 o'clock, the situation of expression match is good more.Through calculating R in the present embodiment ²=0.988, expression match situation is relatively good.

Obtain between roughness and the reflectance relational expression (1-5) afterwards, same batch wafer is detected through optical detector one by one, draw the reflectance of each said wafer, according to relational expression (1-5), obtain the roughness of each said wafer.

Though oneself discloses the present invention as above with preferred embodiment, the present invention is defined in this.Any those skilled in the art are not breaking away from the spirit and scope of the present invention, all can do various changes and modification, so protection scope of the present invention should be as the criterion with claim institute restricted portion.

Claims (4)

1. a detection method of wafer surface roughness is characterized in that comprising the steps:

The wafer of from same batch wafer, picking out at least three different roughness is as sample;

Each said sample is put under the roughness tester detects, draw roughness separately;

Each said sample is put under the optical detector detects, draw reflectance separately;

Set up the relational expression between said roughness and the said reflectance;

Same batch wafer is detected through optical detector one by one, draw the reflectance of each said wafer,, draw the roughness of each said wafer according to said relational expression.

2. detection method of wafer surface roughness according to claim 1 is characterized in that said sample is the wafer of six different roughness.

3. detection method of wafer surface roughness according to claim 1 is characterized in that said relational expression is a linear relation.

4. according to claim 1 or 3 described detection method of wafer surface roughness, the said roughness that it is characterized in that with least square method sample detection being obtained and the value of said reflectance are carried out match, set up said relational expression.

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